Fordonssystem

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Engine laboratory

The engine laboratory is found in direct connection to the main
vehicular corridor. The laboratory is equipped with two engine test
stands, both having modern asynchronous machines capable of both
driving and braking the combustion engines.
The engines are controlled using dSPACE-equipment, with a fully
transparent control system built in Matlab Simulink and executed in
real-time. The main cell measurement system is built around an HP VXi
mainframe, but also a real time Linux computer environment as well as
built in measuring capability of the dSPACE control system hardware is
used extensively.

LNF-engine

Test stand 1 is equipped with a 4 cylinder 2L gasoline engine with 16
valves. The engine uses direct injection, dual variable cam phasing,
and oil cooled pistons. The charging system is a two stage series
sequential turbo system. The low pressure stage is a BorgWarner
K04-2270 turbo (~190.000rpm maximum speed), and the high pressure
turbo is a BorgWarner KP35-1574 (~260.000rpm maximum
speed). Compression ratio is fixed to 9.2:1, and the engine is
"square" with bore equal to stroke (86mm). The base line engine was
installed in 2008, then having a single stage twin scroll turbo
system.

The base line engine was rated at 260hp and 350Nm, however the maximum
power has decreased after the installation of the two stage system in
2009. The two stage system originates from a SAAB 9-3 TTiD
application, and the low pressure stage compressor is smaller than the
original single stage compressor, thus causing the drop in maximum
power. The high pressure stage compressor by-pass has been exchanged
for an actively controlled valve.

Though one can not speak of normal setup, since the engines are for
research, a summary of commonly measured signals is given
here. However, see it only as an indication, and every experiment
normally adds more sensors.
Apart from the cell sensor installation, also engine production
sensors are sampled: Mass flow, pressure before and after main
throttle, temperature before throttle, engine speed and position
(58X), cam phases, fuel rail pressure, vacuum tank pressure, main
throttle position (two sensors), air to fuel ratio (broad band
lambda), and system voltage level.

The (S)AAB (V)ariable (C)ompression engine sits in the second test
stand. The engine has variable compression ratio that can be altered
in real time .
The compression ratio can be varied between roughly 8
and 14. The engine is a 5 cylinder 1.6L gasoline engine with a
mechanical compressor, driven by the engine crank shaft. The
compressor can be disconnected using a magnetic clutch, and by-passed
using a butterfly throttle valve. The engine was originally developed
to replace a 3L natural aspirated V6 engine, thus having performance
target of roughly 200hp and 300Nm.

The SVC is a prototype engine, that has never been in
production. The original concept was developed during the late 80s and
early 90s.
The engine was only hand built in a low number, and due to this
Vehicular Systems have collected roughly 2.5 spare engines. The engine
is said to withstand engine knock.

Control system

The main engine control system is a real time system utilizing
equipment from dSPACE. The system consists of a MicroAutoBox that,
mainly, runs the code and a RapidPro-system that is used mainly as an
I/O-system. The code is compiled from a Simulink model, that is
developed in-house. The control system is fully transparent to the
user, enabling full control of all signals.
The control system development is mainly conducted in the Simulink
environment, from where the compilation of the code is also
done. dSPACE ControlDesk is then used to download the code to the
MABx.

Test stands and test cell equipment

We have two engine test stands suited for testing
passenger car engines. Both test stands are equipped with modern
asynchronous machines which can act both as a drive and a load to the
engines.
These test stands gives us the possibility to run both steady state
and dynamic tests, with torque rise-times less than 10 ms. The
dynamometers can be used to simulate vehicle behavior, and run test
cycles (e.g. NEDC, FTP75). By connecting the measurement system to the
dynamometer and letting the measurement system control the behavior of
the dynamometer we do automatic engine mapping and cycle tests.
The sensory equipment of the dynamometers include a shaft speed
sensor, as well as applied torque. The test cell is restricted to only
operate one engine at a time.

The electricity produced by the dynamometer, when loading the engines,
is fed back to the B-building, through a dedicated transformer station
located in the engine lab building. The coolant water also
recirculates, and contributes to the heating of the B-building. The
fuel supply to the engines is found in a dedicated, highly ventilated,
room. Fuel is pumped, using compressed air pumps, from the fuel
storage room into 12L tanks inside the engine test stand
room. Production fuel pumps then feed the fuel rails of the engines.

Both dynamometers were replaced after a small fire in year 2001. The
new dynamometers are asynchronous machines delivered from Schenck and have a braking
capability of 250 kW (~340 hp) and a rated torque of 480 Nm. The
dynamometers also act as start motors for the combustion engines.

Test stand 1 and 2

Type

Schenck Dynas3 LI 250

Power [kW]

250

MaximumSpeed [rpm]

10 000

RatedTorque [Nm]

480

Main characteristics of the test stands

Measurement equipment

Three measurement systems are currently used in the engine test
laboratory; an HP VXI system, a dSPACE RapidPro/MicroAutoBox
system, and a real-time capable Linux computer with an NI I/O-card.
The VXI mainframe is fitted with a fast 8 channel digitizer + DSP
capable of anti-alias protected sampling up to 196 kHz/ch and a slower
module more suited for stationary measurement of up to 64 channels of
combined voltage, temperature, current and frequency input/outputs.
The slower module is also capable of closed loop control. All VXI
components are delivered by Hewlett-Packard.
The dSPACE equipment is mainly used as the real time control system of
the engines, but is also capable of measuring both analogue and
digital signals with sampling frequencies up to CAD-based.
The real-time Linux computer is also capable of control, but is
currently mainly used as to graphically present and analyze
in-cylinder pressures.